<div class="grid">
  <div></div>
  <div></div>
  <div></div>
</div>

.grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: 100px 1fr 2fr;
  margin: 0 0 1rem 0;
}

.grid > div {
  height: 100px;
  background: red;
}

body {
  margin: 1rem;
}